2026 ICD-10-CM Diagnosis Code Z23Encounter for immunization
Z23 is a billable ICD-10-CM diagnosis code for encounter for immunization. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Exposure, encounters, screening or contact with infectious disease.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for Z23.
Present on Admission (POA)Billing
Z23 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- 1st Hib and DTP vaccine given
- 2nd Hib and DTP vaccine given
- 3rd Hib and DTP vaccine given
- Administration of human papilloma virus type 6, 11, 16, and 18 vaccine done
- Bacillus Calmette-Guerin vaccination given
- Cholera vaccination given
- Diphtheria and acellular pertussis and inactivated poliomyelitis and tetanus vaccination given
- Diphtheria and tetanus and acellular pertussis and Haemophilus influenzae type b and inactivated poliomyelitis vaccination given
- Diphtheria and tetanus and acellular pertussis and Hepatitis b and inactivated poliomyelitis vaccination given
- Diphtheria and tetanus vaccination given
- Diphtheria vaccination given
- Diphtheria, tetanus and acellular pertussis vaccination given
- Diphtheria, tetanus, pertussis and polio vaccination given
- Haemophilus influenza type B vaccination given
- Has influenza vaccination at home
- Has influenza vaccination at hospital
- Has influenza vaccination at surgery
- Has influenza vaccination at work
- Herpes zoster vaccination given
- Human papilloma virus type 16 and 18 vaccination given
- Human papilloma virus vaccination given
- Human papillomavirus 6, 11, 16, 18, 31, 33, 45, 52 and 58 vaccination given
- Influenza A H1N1 vaccination given
- Influenza vaccination given
- Influenza vaccination requested
- Influenza vaccination status
- Intranasal influenza vaccination given
- Measles vaccination given
- Measles vaccination requested
- Measles, mumps and rubella vaccination given
- Meningococcus vaccination given
- Mumps vaccination given
- Pneumococcal 13-valent conjugate vaccination given
- Pneumococcal 20-valent conjugate vaccination given
- Pneumococcal 23-valent polysaccharide vaccination given
- Pneumococcal 7-valent conjugate vaccination given
- Pneumococcal vaccination given
- Poliomyelitis vaccination given
- Procedure needed
- Rabies vaccination given
- Respiratory syncytial virus vaccination given
- Rotavirus vaccination given
- Rubella vaccination given
- Tetanus toxoid vaccination given
- Travel vaccination given
- Typhoid vaccination given
- Vaccination given
- Vaccination needed
- Varicella-zoster vaccination for chicken pox given
- Varicella-zoster vaccination given
- Viral hepatitis A and B vaccination given
- Viral hepatitis A vaccination given
- Viral hepatitis B vaccination given
- Yellow fever vaccination given
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Code First
- any routine childhood examination
Code Also
- , if applicable, encounter for immunization safety counseling Z71.85
- procedure codes are required to identify the types of immunizations given
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
A "code also" note instructs that two codes may be required to fully describe a condition, but this note does not provide sequencing direction.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
- Admission (for) - See Also: Encounter (for);
- prophylactic (measure) - See Also: Encounter, prophylactic measures;
- vaccination - Z23
- Immunization - See Also: Vaccination;
- encounter for - Z23
- vaccination - Z23
- encounter for - Z23
External Cause of Injuries IndexGuidance
References for this code in the External Cause of Injuries Index.
- Admission(for)
- prophylactic (measure)
- vaccination
- Immunization
- encounter for
- Prophylactic
- vaccination
- Vaccination(prophylactic)
- encounter for
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Vaccines
Vaccines are injections (shots), liquids, pills, or nasal sprays that you take to teach your body's immune system to recognize and defend against harmful germs. For example, there are vaccines to protect against diseases caused by:
The full article covers:
- What are vaccines?
- What are the types of vaccines?
- What happens in an immune response?
- What are immunization and vaccination?
- Why are vaccines important?
- What is community immunity?
- Are vaccines safe?
- What is a vaccine schedule?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert Z23 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Z23Overview
Is Z23 (Encounter for immunization) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report encounter for immunization on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Can Z23 be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because encounter for immunization describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
Is Z23 exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for encounter for immunization on inpatient claims.
What is the ICD-9 equivalent of Z23?
Under the General Equivalence Mappings, encounter for immunization converts to ICD-9-CM V05.9 (vaccin for singl dis NOS). The mapping is approximate, so confirm the match fits the documentation.
